To understand the variety of structures we have in our memories, let's consider an example memory task. How good an answer can you give to this question:
When was Bill Clinton born?
Now think about how you answered the question. Different people answer this question in different ways. Most people use one of these three strategies:
Strategy 1) They know the answer immediately.
Strategy 2) They know how old Clinton was at some important point (such as when he was inaugurated President) and do some simple math to figure out how old he is now.
Strategy 3) They don't know how old he is, but try to figure it out by comparing him to another individual whose age they know. So, a high-schooler might guess that Clinton is the age of the high-schooler's parents. A senior citizen might compare Clinton to one of their children.
Each of these strategies uses different memory structures. The first strategy is simple: locate the fact in memory that gives the answer. The second strategy is more complex: locate some episode in memory which gives an age for Clinton and then use that episode to calculate the desired value. The third strategy is also more complex: locate some "reference" individual and use that individual's age, perhaps adjusting it a bit one way or the other.
All three strategies use some bottom-level knowledge structure as input data. The first strategy requires a single fact: Clinton's age. The second strategy requires a bit more knowledge: Clinton's age at some point in time and when that point was. The last strategy is more complex. It requires locating a person who seems similar in age to Clinton, figuring out how old that person is, and then perhaps adjusting the answer a bit. In order to use this strategy, one must know a lot more than a single decontextualized fact. One must know enough about the reference person to be able to bring them to mind in the first place as well as to be able to adjust their age before responding. We call the structure that holds this latter sort of knowledge a "case."
The Purpose of Memory Structures
Where am I in the content of the book?